1. Field of Invention
This invention pertains to a tufted air mattress formed of three congruent thermoplastic sheets with two of the sheets printed with a fluoropolymer containing ink before being heat sealed. More particularly, this invention pertains to a therapy system including the tufted air mattress, which includes two chambers for containing air, that is inflated from an air supply passing through an alternating air supply valve, which inflates each chamber individually and sequentially in an alternating manner, while deflating the other chamber.
2. Description of the Related Art
Inflatable thermal mattresses are often used in medical environments to support patients and to provide thermal conditioning to patients. For patients who are bedridden or who are immobilized for long periods of time, the prevention of skin rashes and bed sores caused by pressure applied by the mattress to the patient is a concern.
Many diverse air mattresses are known in the art. For example, U.S. Pat. No. 4,347,633, titled “Patient treating mattress,” issued to Gammons, et al., on Sep. 7, 1982, and U.S. Pat. No. 4,472,847, with the same title and issued to Gammons, et al., on Sep. 25, 1984, disclose crawl resistant flexible mattresses formed of panels sealed together. Both patents disclose mattresses with inflatable passages and a top surface with vent holes for exhausting conditioned air to ventilate the patient. The mattresses are formed of panels sealed together, and either one or both of the panels can be preformed by vacuum or pressure molding. The patents disclose heat sealing the top and bottom panels through a fusion process, but does not provide additional details on the fusion process.
U.S. Pat. No. 4,149,541, titled “Fluid circulating pad,” issued to Gammons, et al., on Apr. 17, 1979, discloses a flexible pad with interconnecting waffle-grid patterned passages. The pad is formed of a pair of flexible thermoplastic panels sealed together about a peripheral seal. The patent does not provide any details regarding how the seals are formed.
U.S. Pat. No. 6,102,936, titled Inflatable thermal pad with drainage,” issued to Augustine, et al., on Aug. 15, 2000, discloses an inflatable convective thermal pad for use under a patient. The pad is formed of two layers joined and sealed at their periphery and at various other points. The patent discloses ultrasonic welding as one technique that may be used to form a seal between the layers. The patent also discloses alternative techniques of RF sealing or heat sealing, without providing any details as to how these techniques are applied to form the thermal pad.
U.S. Pat. No. 3,653,083, titled “Bed pad,” issued to Lapidus on Apr. 4, 1972, discloses an aerated bed pad that has a variable flexing motion. In one embodiment, the pad includes a tubular member that alternately inflates and deflates, and the tubular member is interlaced with resilient strips that provide a floor on deflation. In another embodiment, the pad includes two interlaced tubular members that are alternately inflated and deflated. The pad if formed of two sheets of relatively think plastic, such as vinyl plastic, that are vacuum formed and heat sealed. Although the patent discloses heat sealing as the technique for forming a seal between the two sheets, it does not provide any details as to how heat sealing is applied to the sheets to form the pad.
Various techniques of forming inflatable mattresses and pads are used. One such technique is to glue or apply an adhesive or solvent between the two sheets of material forming the mattress. Another technique is to ultrasonically weld the two materials to form a seal.
Still another technique is to heat seal. Heat sealing involves applying heat to the area where the seal is desired. One method of applying heat to selected areas is by using a heated die with a raised pattern corresponding to the areas to be sealed. For mattresses, which are large, this method is cumbersome because it requires a heated die the size of the mattress. A similar method is by ultrasonic welding of selected areas.
Another method is to place a third sheet of incompatible material between the two sheets before applying heat to the three sheets. The third sheet is sized and has openings arranged so as to allow the two thermoplastic sheets to fuse while preventing the two sheets fusing where the third sheet is interposed. While this method allows the use of heated roller to heat seal, it also requires the use and handling of a third sheet, which increases the production costs.
U.S. Pat. No. 5,022,109. titled “Inflatable bladder,” issued to Pekar on Jun. 11, 1991, discloses a variation on ultrasonic welding in which three layers of sheets form the mattress, but only two sheets are welded together at any one spot. Heat energy, such as by ultrasonic welding, is applied to the sheets in specific areas in order to form seals. Barrier coatings, or coated bands, are applied in alternating strips on both sides of the middle sheet. The barrier coatings allow one outside sheet and the middle sheet to be sealed on one side of the middle sheet and the coating prevents the other outside sheet from sealing to the middle sheet at the same location. The barrier coatings act as a prophylactic by preventing the heat energy applied to specific areas of the sheets from welding, or fusing, two of the sheets together.
It is an objective of the present invention to provide an economical way of fabricating a tufted air mattress by heat sealing with heat applied to the full surface of the mattress, as opposed to localized, or spot, welding.
It is another objective of the present invention to provide areas on a thermoplastic sheet defining a connection between adjacent sheets when heat is applied to the full area of the mattress or bladder.
It is still another objective of the present invention to provide two isolated chambers that are inflated and deflated in an alternating manner.